Saturn
Saturn,The Famous Gas giant Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to theGreek Cronus (the Titan father of Zeus), the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol (♄) represents the Roman god's sickle. Saturn, along with Jupiter, Uranus and Neptune, is a gas giant. Together, these four planets are sometimes referred to as the Jovian planets, meaning "Jupiter-like". Saturn has an average radius about 9 times larger than the Earth's.[12][13] While only 1/8 the average density of Earth, due to its larger volume, Saturn's mass is just over 95 times greater than Earth's.[14][15][16] Because of Saturn's large mass and resulting gravitation, the conditions produced on Saturn are extreme if compared to Earth. The interior of Saturn is probably composed of a core of iron, nickel, silicon and oxygen compounds, surrounded by a deep layer ofmetallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium and finally, an outer gaseous layer.[17] Electrical current within the metallic-hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is slightly weaker than Earth's and approximately one-twentieth the strength of Jupiter's.[18] The outeratmosphere is generally bland in appearance, although long-lived features can appear.Wind speeds on Saturn can reach 1,800 km/h, significantly faster than those on Jupiter. Saturn has a ring system that is divided into nine continuous and three discontinuous main rings (arcs), consisting mostly of ice particles with a smaller amount of rocky debris and dust. Sixty-two[19] known moons orbit the planet; fifty-three are officially named. This does not include the hundreds of "moonlets" within the rings. Titan, Saturn's largest and the Solar System's second largest moon (after Jupiter's Ganymede), is larger than the planet Mercury and is the only moon in the Solar System to possess a significant atmosphere.[20] Planetary Rings Saturn is probably best known for its system of planetary rings, which makes it the most visually remarkable object in the solar system.24 The rings extend from 6,630 km to 120,700 km above Saturn's equator, average approximately 20 meters in thickness and are composed of 93% water ice with a smattering of tholin impurities and 7% amorphous carbon.63 The particles that make up the rings range in size from specks of dust up to 10 m.64 There are two main theories regarding the origin of the rings. One theory is that the rings are remnants of a destroyed moon of Saturn. The second theory is that the rings are left over from the original nebular material from which Saturn formed. Some ice in the central rings comes from the moon Enceladus' ice volcanoes.65 Beyond the main rings at a distance of 12 million km from the planet is the sparse Phoebe ring, which is tilted at an angle of 27° to the other rings and, like Phoebe, orbits in retrograde fashion.66 Some of the moons of Saturn, including Pan and Prometheus, act as shepherd moons to keep the planetary rings stable and prevent them from escaping.67 Pan and Atlas cause weak, linear density waves in Saturn's rings that have yielded more reliable calculations of their masses.68 The age of these planetary rings is probably hundreds of millions of years old69 (in contrast to previous thoughts that the rings formed alongside the planet when it formed billions of years ago)70 and their fate include spiraling inward towards the planet, or the boulders forming the rings colliding with each other and disappearing.